scholarly journals Accelerated mass loss of Himalayan glaciers since the Little Ice Age

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ethan Lee ◽  
Jonathan L. Carrivick ◽  
Duncan J. Quincey ◽  
Simon J. Cook ◽  
William H. M. James ◽  
...  
Keyword(s):  
Mass Loss ◽  
Little Ice Age ◽  
Ice Age ◽  
Orographic Effects ◽  
Rates Of Change ◽  
Himalayan Glaciers ◽  
Order Of Magnitude ◽  
The Himalaya ◽  
Rapid Mass

AbstractHimalayan glaciers are undergoing rapid mass loss but rates of contemporary change lack long-term (centennial-scale) context. Here, we reconstruct the extent and surfaces of 14,798 Himalayan glaciers during the Little Ice Age (LIA), 400 to 700 years ago. We show that they have lost at least 40 % of their LIA area and between 390 and 586 km3 of ice; 0.92 to 1.38 mm Sea Level Equivalent. The long-term rate of ice mass loss since the LIA has been between − 0.011 and − 0.020 m w.e./year, which is an order of magnitude lower than contemporary rates reported in the literature. Rates of mass loss depend on monsoon influence and orographic effects, with the fastest losses measured in East Nepal and in Bhutan north of the main divide. Locally, rates of loss were enhanced with the presence of surface debris cover (by 2 times vs clean-ice) and/or a proglacial lake (by 2.5 times vs land-terminating). The ten-fold acceleration in ice loss we have observed across the Himalaya far exceeds any centennial-scale rates of change that have been recorded elsewhere in the world.

scholarly journals Himalayan glaciers experienced significant mass loss during later phases of little ice age

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Mayank Shekhar ◽  
Anshuman Bhardwaj ◽  
Shaktiman Singh ◽  
Parminder S. Ranhotra ◽  
Amalava Bhattacharyya ◽  
...  
Keyword(s):  
Mass Loss ◽  
Little Ice Age ◽  
Ice Age ◽  
Himalayan Glaciers ◽  
Significant Mass Loss ◽  
Significant Mass

scholarly journals Simulated retreat of Jakobshavn Isbræ since the Little Ice Age controlled by geometry

2018 ◽  
Vol 12 (7) ◽  
pp. 2249-2266 ◽  
Author(s):  
Nadine Steiger ◽  
Kerim H. Nisancioglu ◽  
Henning Åkesson ◽  
Basile de Fleurian ◽  
Faezeh M. Nick
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Climate Forcing ◽  
Relative Role ◽  
Regional Warming ◽  
History Of ◽  
The Impact ◽  
Term Response

Abstract. Rapid retreat of Greenland's marine-terminating glaciers coincides with regional warming trends, which have broadly been used to explain these rapid changes. However, outlet glaciers within similar climate regimes experience widely contrasting retreat patterns, suggesting that the local fjord geometry could be an important additional factor. To assess the relative role of climate and fjord geometry, we use the retreat history of Jakobshavn Isbræ, West Greenland, since the Little Ice Age (LIA) maximum in 1850 as a baseline for the parameterization of a depth- and width-integrated ice flow model. The impact of fjord geometry is isolated by using a linearly increasing climate forcing since the LIA and testing a range of simplified geometries. We find that the total length of retreat is determined by external factors – such as hydrofracturing, submarine melt and buttressing by sea ice – whereas the retreat pattern is governed by the fjord geometry. Narrow and shallow areas provide pinning points and cause delayed but rapid retreat without additional climate warming, after decades of grounding line stability. We suggest that these geometric pinning points may be used to locate potential sites for moraine formation and to predict the long-term response of the glacier. As a consequence, to assess the impact of climate on the retreat history of a glacier, each system has to be analyzed with knowledge of its historic retreat and the local fjord geometry.

scholarly journals Moisture Changes in the Northern Xinjiang Basin Over the Past 2400 years as Documented in Pollen Records of Jili Lake

2021 ◽  
Vol 9 ◽  
Author(s):  
Yulin Xiao ◽  
Lixiong Xiang ◽  
Xiaozhong Huang ◽  
Keely Mills ◽  
Jun Zhang ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Terrestrial Ecosystem ◽  
Warm Period ◽  
Ice Age ◽  
Pollen Record ◽  
Humid Climate ◽  
Northern Xinjiang ◽  
The Past ◽  
Climate Background

Regional humidity is important for terrestrial ecosystem development, while it differs from region to region in inland Asia, knowledge of past moisture changes in the lower basin of northern Xinjiang remainly largely unclear. Based on a pollen record from Jili Lake, the Artemisia/(Amaranthaceae + Ephedra) (Ar/(Am + E)) ratio, as an index of regional humidity, has recorded four relatively dry phases: 1) 400 BCE to 1 CE, 2) the Roman Warm Period (RWP; c. 1–400 CE), 3) the Medieval Warm Period (MWP; c. 850–1200 CE) and 4) the Current Warm Period (CWP; since 1850 CE). In contrast, the Dark Age Cold Period (DACP; c. 400–850 CE) and the Little Ice Age (LIA; c. 1200–1850 CE) were relatively wet. Lower lake levels in a relatively humid climate background indicated by higher aquatic pollen (Typha and Sparganium) after c. 1700 CE are likely the result of intensified irrigation for agriculture in the catchment as documented in historical records. The pollen Ar/(Am + E) ratio also recorded a millennial-scale wetting trend from 1 CE to 1550 CE which is concomitant with a long-term cooling recorded in the Northern Hemisphere.

scholarly journals Glacier dynamics at Helheim and Kangerdlugssuaq glaciers, southeast Greenland, since the Little Ice Age

2014 ◽  
Vol 8 (1) ◽  
pp. 1257-1278
Author(s):  
S. A. Khan ◽  
K. K. Kjeldsen ◽  
K. H. Kjær ◽  
S. Bevan ◽  
A. Luckman ◽  
...  
Keyword(s):  
Mass Balance ◽  
Little Ice Age ◽  
Initial Conditions ◽  
Ice Age ◽  
Short Term ◽  
Episodic Events ◽  
Highly Sensitive ◽  
Decadal Scale ◽  
Speed Up

Abstract. Observations over the past decade show significant ice loss associated with the speed-up of glaciers in southeast Greenland from 2003, followed by a deceleration from 2006. These short-term, episodic, dynamic perturbations have a major impact on the mass balance at the decadal scale. To improve the projection of future sea level rise, a long-term data record that reveals the mass balance beyond such episodic events is required. Here, we extend the observational record of marginal thinning of Helheim glacier (HG) and Kangerdlugssuaq glacier (KG) from 10 to more than 150 yr. We show that although the frontal portion of HG thinned by more than 100 m between 2003 and 2006, it thickened by more than 50 m during the previous two decades. In contrast, KG was stable from 1981 to 1998 and experienced major thinning only after 2003. Extending the record back to the end of the Little Ice Age (ca. 1850) shows no significant thinning of HG from 1850 to 1981, while KG underwent substantial thinning of ~265 m. Analyses of their sensitivity to sub-surface water temperature anomalies and variations in air temperature suggest that both HG and KG are highly sensitive to short-term atmospheric and ocean forcing, and respond very quickly to small fluctuations. At century time-scales, however, multiple external parameters (e.g. outlet shape) dominate the mass change. These findings undermine attempts to use measurements over the last decade as initial conditions to project future dynamic ice loss.

scholarly journals Was the Little Ice Age more or less El Niño-like than the Medieval Climate Anomaly? Evidence from hydrological and temperature proxy data

2017 ◽  
Vol 13 (3) ◽  
pp. 267-301 ◽  
Author(s):  
Lilo M. K. Henke ◽  
F. Hugo Lambert ◽  
Dan J. Charman
Keyword(s):  
Little Ice Age ◽  
Large Scale ◽  
Global Climate ◽  
Ice Age ◽  
Medieval Climate Anomaly ◽  
Climate Anomaly ◽  
Proxy Data ◽  
The Past ◽  
Proxy Records

Abstract. The El Niño–Southern Oscillation (ENSO) is the most important source of global climate variability on interannual timescales and has substantial environmental and socio-economic consequences. However, it is unclear how it interacts with large-scale climate states over longer (decadal to centennial) timescales. The instrumental ENSO record is too short for analysing long-term trends and variability and climate models are unable to accurately simulate past ENSO states. Proxy data are used to extend the record, but different proxy sources have produced dissimilar reconstructions of long-term ENSO-like climate change, with some evidence for a temperature–precipitation divergence in ENSO-like climate over the past millennium, in particular during the Medieval Climate Anomaly (MCA; AD  ∼  800–1300) and the Little Ice Age (LIA; AD  ∼  1400–1850). This throws into question the stability of the modern ENSO system and its links to the global climate, which has implications for future projections. Here we use a new statistical approach using weighting based on empirical orthogonal function (EOF) to create two new large-scale reconstructions of ENSO-like climate change derived independently from precipitation proxies and temperature proxies. The method is developed and validated using model-derived pseudo-proxy experiments that address the effects of proxy dating error, resolution, and noise to improve uncertainty estimations. We find no evidence that temperature and precipitation disagree over the ENSO-like state over the past millennium, but neither do they agree strongly. There is no statistically significant difference between the MCA and the LIA in either reconstruction. However, the temperature reconstruction suffers from a lack of high-quality proxy records located in ENSO-sensitive regions, which limits its ability to capture the large-scale ENSO signal. Further expansion of the palaeo-database and improvements to instrumental, satellite, and model representations of ENSO are needed to fully resolve the discrepancies found among proxy records and establish the long-term stability of this important mode of climatic variability.

Climatic Fluctuations in Northern Patagonia during the Last 1000 Years as Inferred from Tree-Ring Records

1990 ◽  
Vol 34 (3) ◽  
pp. 346-360 ◽  
Author(s):  
Ricardo Villalba
Keyword(s):  
Tree Ring ◽  
Little Ice Age ◽  
Ice Age ◽  
Dry Period ◽  
Climatic Fluctuations ◽  
Northern Patagonia ◽  
The Andes ◽  
Weather Stations ◽  
Fitzroya Cupressoides

AbstractMillennium-old alerce trees (Fitzroya cupressoides (Mol.) Johnst.) have been used to develop a 1120-year reconstruction of the summer temperature departures for the Andes of northern Patagonia in Argentina. Four main climatic episodes can be distinguished in this proxy paleoclimatic record. The first, a cold and moist interval from A.D. 900 to 1070, was followed by a warm-dry period from A.D. 1080 to 1250 correlative with the Medieval warm epoch of Europe. Afterward, a long, cold-moist period followed from A.D. 1270 to 1670, peaking around A.D. 1340 and 1650. These cold maxima are contemporaneous with two principal Little Ice Age events registered in the Northern Hemisphere. Warmer conditions then resumed between A.D. 1720 and 1790. These episodes are supported by glaciological and palynological data in Patagonia. Following a cold period in the early 1800s, tree-ring indices have oscillated around the long-term mean, except for a warmer period from A.D. 1850 to 1890. Correlations between the Rio Alerce reconstruction and the regional weather stations indicate that the tree-ring variations are correlated with a homogeneous summer weather pattern covering Patagonia east of the Andes from 38° to 50°S.

scholarly journals Present Glaciers of Tavan Bogd Mountain Massif and Their Changes Since the LIA

2018 ◽  
Author(s):  
Dmitry A. Ganyushkin ◽  
Kirill V. Chistyakov ◽  
Ilya V. Volkov ◽  
Dmitry V. Bantcev ◽  
Elena P. Kunaeva ◽  
...  
Keyword(s):  
Data Analysis ◽  
Little Ice Age ◽  
Field Studies ◽  
Ice Age ◽  
Relative Reduction ◽  
Glacial Retreat ◽  
Different Parts ◽  
Term Field

The study is based on the results of long-term field studies, satellite and aerial data analysis. In the maximum of the Little Ice Age (LIA) 243 glaciers with a total area of 353.4 km2 were reconstructed. By the results of interpretation of Corona images by 1968 the number of glaciers increased (236), the total area reduced to 242 km2. In 2010 glaciation was represented by 237 glaciers with a total area of 201 km2. Thus, from the maximum of the LIA, the glaciation of the Tavan-Bogd mountains decreased by 43%, which is somewhat less than the neighboring glacial centers (Ikh-Turgen, Tsambagarav, Tsengel-Khayrkhan and Mongun-Taiga mountains). The probable cause is the predominance of larger glaciers relatively resistant to warming and higher altitudes. The effect of glacier size on their stability is supported by differences in the relative shrinkage of glaciers in different parts of the Tavan-Bogdo-Ola massif: the smallest decline occurred in the basins of the Tsagan-Gol (31.7%) and Sangadir (36.4%) rivers where the largest glaciers are located. On the contrary, on the lower periphery of the massif, where small glaciers predominate, the relative reduction was large (74-79%). On the background of the general retreat trend large valleys glaciers retreated faster in 1968-1977 and after 2010. In 1990-s the retreat was slow. After 2010 the glacial retreat was extremely fast. The retreat of glaciers in the last 50-60 years was caused by a trend towards a decrease in the amount of precipitation until the mid-1970s and a sharp warming in the 1990s and early 2000s.

scholarly journals Lateral variation in slab window viscosity inferred from global navigation satellite system (GNSS)–observed uplift due to recent mass loss at Patagonia ice fields

Geology ◽  
2021 ◽  
Author(s):  
Raymond M. Russo ◽  
Haipeng Luo ◽  
Kelin Wang ◽  
Boudewijn Ambrosius ◽  
Victor Mocanu ◽  
...  
Keyword(s):  
Mass Loss ◽  
Three Dimensional ◽  
Element Model ◽  
Satellite System ◽  
Ice Age ◽  
Ridge Subduction ◽  
The North ◽  
Order Of Magnitude ◽  
Ice Field ◽  
Slab Window

The geographic coincidence of the Chile Ridge slab window and the Patagonia ice fields offers a unique opportunity for assessing the effects of slab window rheology on glacial isostatic adjustment (GIA). Mass loss of these ice fields since the Little Ice Age causes rapid but variable crustal uplift, 12–24 mm/yr around the North Patagonia ice field, increasing to a maximum of 41 mm/yr around the South Patagonia ice field, as determined from newly collected or processed geodetic data. We used these observational constraints in a three-dimensional Maxwell viscoelastic finite element model of GIA response above both the subducting slab and slab window in which the upper-mantle viscosity was parameterized to be uniform with depth. We found that the viscosity of the northern part of the slab window, ~2 × 1018 Pa·s, is lower than that of the southern part by approximately an order of magnitude. We propose that this along-strike viscosity contrast is due to late Cenozoic ridge subduction beneath the northern part of the slab window, which increases asthenospheric temperature and reduces viscosity.

scholarly journals Evolution of Ossoue Glacier (French Pyrenees) since the end of the Little Ice Age

2015 ◽  
Vol 9 (2) ◽  
pp. 2431-2494 ◽  
Author(s):  
R. Marti ◽  
S. Gascoin ◽  
T. Houet ◽  
O. Ribière ◽  
D. Laffly ◽  
...  
Keyword(s):  
Mass Balance ◽  
Little Ice Age ◽  
Atlantic Multidecadal Oscillation ◽  
Ablation Rate ◽  
Ice Age ◽  
Glacier Length ◽  
Geodetic Mass Balance ◽  
High Elevations ◽  
Topographic Surveys

Abstract. Long-term climate records are rare at high elevations in Southern Europe. Here, we reconstructed the evolution of Ossoue Glacier (42°46' N, 0.45 km2), located in the Pyrenees (3404 m a.s.l.), since the Little Ice Age (LIA). Glacier length, area, thickness and mass changes indicators were generated from historical datasets, topographic surveys, glaciological measurements (2001–2013), a GPR survey (2006) and stereoscopic satellite images (2013). The glacier has receded considerably since the end of the LIA, losing 40 % of its length and 60% of its area. Three periods of marked ice depletion can be identified: 1850–1890, 1928–1950 and 1983–2013, as well as two periods of stabilization or slightly growth: 1905–1928 and 1950–1983; these agree with climatic datasets (air temperature, precipitation, North Atlantic Oscillation, Atlantic Multidecadal Oscillation). In the early 2000s, the area of the glacier dropped below 50% of its area at the end of the LIA. Geodetic mass balance measurements over 1983–2013 indicated −30.1 ± 1.7 m w.e. (−1 m w.e. yr−1) whereas glaciological mass balance measurements show −17.36 ± 2.9 m w.e. (−1.45 m w.e. yr−1) over 2001–2013, resulting in a doubling of the ablation rate in the last decade. In 2013 the maximum ice thickness was 59 ± 10.3 m. Assuming that the current ablation rate stays constant, Ossoue Glacier will disappear midway through the 21st century.

scholarly journals Rainfall variability in southeast and west-central Africa during the Little Ice Age: do documentary and proxy records agree?

2021 ◽  
Vol 168 (1-2) ◽  
Author(s):  
Matthew J. Hannaford ◽  
Kristen K. Beck
Keyword(s):  
Southern Africa ◽  
Little Ice Age ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Central Africa ◽  
Ice Age ◽  
West Central ◽  
Early Colonial ◽  
Instrumental Records

AbstractUnderstanding of long-term climatic change prior to instrumental records necessitates reconstructions from documentary and palaeoclimate archives. In southern Africa, documentary-derived chronologies of nineteenth century rainfall variability and palaeoclimate records have permitted new insights into rainfall variability over past centuries. Rarely considered, however, is the climatic information within early colonial documentary records that emerge from the late fifteenth century onwards. This paper examines evidence for (multi-)seasonal dry and wet events within these earlier written records (c. 1550–1830 CE) from southeast Africa (Mozambique) and west-central Africa (Angola) in conjunction with palaeoclimate records from multiple proxies. Specifically, it aims to understand whether these sources agree in their signals of rainfall variability over a 280-year period covering the ‘main phase’ Little Ice Age (LIA) in southern Africa. The two source types generally, but do not always, show agreement within the two regions. This appears to reflect both the nature of rainfall variability and the context behind documentary recording. Both source types indicate that southeast and west-central Africa were distinct regions of rainfall variability over seasonal and longer timescales during the LIA, with southeast Africa being generally drier and west-central Africa generally wetter. However, the documentary records reveal considerable variability within these mean state climatic conditions, with multi-year droughts a recurrent feature in both regions. An analysis of long-term rainfall links with the El Niño–Southern Oscillation (ENSO) in southeast Africa suggests a complex and possibly non-stationary relationship. Overall, early colonial records provide valuable information for constraining hydroclimate variability where palaeoclimate records remain sparse.

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